Method and device for disintegrating coarse material

ABSTRACT

Coarse waste such as stumps, lumber from demolition and the like is disintegrated in accordance with a method and device comprising at least two cooperating, essentially parallel screws having threads with disintegrating edges which move in mutually opposite feeding directions so that they tear the waste into pieces.

TECHNICAL FIELD

The present invention relates to a method and a device fordesintegrating coarse and voluminous non-friable material, e.g. stumps,peat and waste from clearing, demolition and packing etc. to desirablefractions for e.g. making cellulose, fuel, compost and the like.

PRIOR ART

This type of handling demands large machines with heavy expenses. Themachine types, which alrady are available on the market, have heavyconsumption of energy and proportionately low production capacity at thesame time as they have a limited capacity to accept and desintegratevery bulky material.

A large group of machines for this purpose desintegrate the material byfeeding the same toward one or several constrictions by means of one orseveral parallel screws. This is a very energy demanding method becauseof the friction in the constriction.

Another group of machines (SE-patent No. 409 420) have screws whichabove a bottom feed the material forwardly toward stationary dollyknives. A problem herewith is a.o. that the material may stop againstthe knives. To reduce this problem it is suggested in the patent tointermittently and individually reverse the operation of the screws tofeed back the material which possibly have stopped. However, this doesnot prevent that these machines have defective capacity.

A third group of machines for this purpose operate with propeller likescrew members which principally divide the material in a tangentialdirection against dollies in form of counteracting rotors or fixedprojections from surrounding stand walls. Also machines with rapidlyrotating striking members e.g. hammer mills have been used todesintegrate coarse waste, but they have limitations regarding thedimension of the material supplied thereto.

THE INVENTION

The present invention relates to a method and a device fordesintegrating coarse material to pieces of desirable dimension withlowest possible energy consumption and with as little too fine materialas possible.

According to the invention the material is desintegrated in a way whichis defined in claim 1. Accordingly, the material will not be fedforwardly by the screws but is torn and crushed between them until itpasses through the spaces between the screws. By choosing a suitabledimension of the spaces between the screws, a desirable dimension of thedesintegrated material can be obtained. Since the screws have acomparatively small pitch in proportion to the diameter of the screw thetangential operating force is geared up to a many times larger axiallyoperating force. The axial forces in two cooperating screws counteracteach other. Accordingly, the material introduced between these screws iseffectd by a counteracting force couple tearing the material in itsweakest sections into pieces. When the material is desintegrated so thatit can fall down through the openings between the screws the material isfinally divided and may be transported away.

The above desintegration effect is obtained along the whole slot betweentwo cooperating screws, which gives a larte production capacity with acomparative small energy consumption. The threads on the screws shouldbe blade shaped and slope in the feeding direction and should be coveredon the edge with a wear resistant material. Counteracting feedingdirections can be provided either by two adjacent screws havingdifferent directions of rotation or by screws having opposite threads,i.e. one is right threaded and the other is left threaded.

The division of the material may also be done in several steps, wherebyit may pass several sets of cooperating screws with gradually decreasingdimensions and mutual distance.

The characteristics of the device according to the invention appears byclaim 6. The screws should be arranged essentially horizontally so thatthe material owing to the gravitation passes between them. Above thescrews a funnel is located and under them an opening for discharge. Inthe latter also a grid and classifying means may be located.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows in principle how material is desintegrated according to theinvention.

FIGS. 2 and 3 show in vertical and horizontal cross section aconstruction according to the invention, FIG. 2 showing a cross sectionalong the line II--II in FIG. 3 and FIG. 3 showing a cross section alongthe line III--III in FIG. 2.

FIG. 4 shows in cross section a preferred shape of the blade thread.

FIGS. 5 and 6 show an industrial application of the invention in theform of a mobile construction in which a device according to theinvention is built in.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 two right threaded screws 1, 2 are shown with oppositedirections of rotation, which accordingly aim to feed the stump 3 lyingon the screws in opposite directions. The threads are blade shaped andslope with the outer edges in the feeding direction. The third screw 6is left threaded and cooperate with the middle screw 2 and have the samedirection of rotation as this. By its direction of rotation the thirdscrew will also aim to pull in the stump 7 between the screws.Accordingly the material will be desintegrated by a combination ofcutting, pressing, tearing and bending movements. The obtained pieces 8pass between the screws.

FIGS. 2 and 3 show a device according to the invention located on astand 11 and comprising a frame 12 with bearings 13 for four screws14-17. Of these screws, the two in the middle 15, 16, are right threadedand the two outermost 14, 17 left threaded. The screws are operated bymotors 18 and their direction of rotation have been indicated by arrows.The threads 19 of the screws are blade shaped and oblique in the feedingdirection as is shown in FIG. 4. The material which is to bedesintegrated is fed in by a funnel 20 and the desintegrated materialfalls out through a discharge opening 21.

The blade thread 25 shown in FIG. 4 lean toward the axle 26 on which itis fixed and is provided with a wear resistant edge 27. It isadvantageous that the desintegrating edge 27 on the screw in question isactive in the feeding direction of the screw. In other words the edge 27should have a lip or a cutting or shearing portion facing in the feedingdirection of the screw so that the edges on two adjacent rotation screwsare capable to grip hold of and cut into the material at the same timefrom two different directions.

The mobile device shown in FIGS. 5 and 6 consists of a tractor 31 withsteering 32 in the middle and connected to a trailer 33. Both areprovided with support legs 34, 35, 36. The trailer is provided with ahoisting crane 37 for loading the material, which is to be desintegratedinto a funnel 38, which leads to a screw device according to theinvention. This consists of three screws 39, 40, 41 operated byhydraulic motors 42. For feeding of these there is a hydraulic assembly43. Under the screws there is a grid 44, which allow fine material e.g.soil and sand particles to pass through during desintegration of stumps.The more coarse material slides on the grid 44 to a transport device 45with which the material may be loaded on another vehicle or be put up ina stack. The screw 40 in the middle is located lower than the other twoand can if its feeding direction is chosen right assist in feeding outthe material on the grid 44. The bearing housings 46, 47, 48 for thescrews are displacable and can be adjusted for different degrees ofcoarseness of the material passing through.

We claim:
 1. A method for producing the disintegration of material,which method comprises:rotating at least two generally adjacent,generally parallel co-operating screws, each of said screws havingthreads which have disintegrating edges which are active in thedirection of advancement of the thread during rotation and arranged sothat each screw has a direction of thread advancement which is oppositeto that of any immediately adjacent screw, and; placing the material tobe desintegrated in contact with the screws whereby the disintegratingedges of the threads grip and cut into the material to be disintegrated,in opposite directions.
 2. The method according to claim 1 wherein thedegree of disintegration is controlled by adjustment of the distancebetween the screws.
 3. The method according to claim 1 or claim 2wherein the material is caused to pass through a plurality of sets ofco-operating screws sequentially, each set in said sequence havingdecreasing thread dimensions and decreasing spaces between adjacentthreads.
 4. A device for producing the disintegration of material,comprising:a frame; at least two screws rotatably mounted to the framein an essentially parallel relationship to one another, said screwshaving thread edges adapted for disintegration of material, which edgesare active in the direction of advancement of the threads when thescrews are rotated in a prescribed direction, and each individual screwhaving a direction of thread advancement, when rotated in its prescribeddirection, which is opposite to the direction of thread advancement ofany immediately adjacent screw when said screw is rotated in its ownprescribed direction, and; drive means for rotating each screw in itsprescribed direction so that the disintegrating edges of the threads ofimmediately adjacent screws advance in mutually opposite directions. 5.The device according to claim 4, wherein the screws are arranged inco-operating pairs and are supported in displacable bearings, thedistances between adjacent bearings being adjustable in a directionperpindicular to the axes of the screws, for the purpose of adjustmentof the distances between the screws, whereby the dimensions of thedisintegrated material can be adjusted.
 6. The device according to claim4 or claim 5 wherein the thread helices of adjacent screws are arrangedin the same direction, and wherein the opposite direction of advancementof immediately adjacent threads is produced by rotating the screws inopposite directions of rotation.
 7. The device according to claim 6,wherein said screws have blade-shaped threads which slope in thedirection of feed.
 8. The device according to claim 7 wherein the edgesof the blade-shaped threads are covered with a wear resistant material.9. The device according to claim 4 or claim 5 wherein the thread helicesof adjacent screws are arranged in the opposite direction, and whereinthe opposite direction of advancement of any immediately adjacentthreads is produced by rotating the screws in same directions ofrotation.
 10. The device according to claim 9, further comprising asurrounding housing adjacent to the frame, opening at the top to afunnel and having a discharge opening at the bottom. PG,17
 11. Thedevice according to claim 10, wherein said screws have blade-shapedthreads which slope in the direction of feed.
 12. The device accordingto claim 11, wherein the edges of the blade-shaped threads are coveredwith a wear resistant material.
 13. The device according to claim 9,wherein said screws have blade-shaped threads which slope in thedirection of feed.
 14. The device according to claim 13, wherein theedges of the blade-shaped threads are covered with a wear resistantmaterial.
 15. The device according to claim 4 or claim 5, furthercomprising a surrounding housing adjacent to the frame, opening at thetop of a funnel, and having a discharge opening at the bottom.
 16. Thedevice according to claim 15, wherein said screws have blade-shapedthreads which slope in the direction of feed.
 17. The device accordingto claim 16, wherein the edges of the blade-shaped threads are coveredwith a wear resistant material.
 18. The device according to claim 4 orclaim 5, wherein said screws have blade-shaped threads which slope inthe direction of feed.
 19. The device according to claim 18, wherein theedges of the blade-shaped threads are covered with a wear resistantmaterial.
 20. The device according to claim 4 or 5, wherein said screwshave blade-shaped threads which slope in the direction of feed.
 21. Thedevice according to claim 20, wherein the edges of the blade-shapedthreads are covered with a wear resistant material.